The conventional rails are used to the drawers of furniture or the chassis on the computer rack so as to support the slide of the drawer or the chassis. Generally, the bearing assembly includes a plurality of bearings which allow the rails to be easily pulled relative to another. However, when the rails are pulled to a distance, the portions of the rails that are not overlapped to each other cannot retain the bearings therein, so that the conventional bearing assembly has a bearing retainer to retain the bearings. The bearing retainer separates the bearings so that the bearings are not in contact with each other.
The bearing assembly provides the sliding action between the rails and must include a stop base to avoid the bearing assembly from dropping from the rails. Therefore, the rails have a stop base to stop the bearing assembly and the front end of the rails is used to support the inner rail that is pulled out from the outer rail.
As for the minimum distance and the maximum distance between the two rails to be retracted or expanded, the two-section rails and the bearing assembly are free to slide. When retracting the rails, the rails are pushed to the very end and the bearing assembly is always located between the rails. However, when the rails are pulled to the extreme expanding position, the bearing assembly is shifted by the friction of the inner rail so that it may not move to the desired position. In other words, the bearing assembly does not move to the maximum distance with the inner rail, the bearing assembly is stopped by the stop base when it moves to the maximum distance. When the rails are retracted at the status that the bearing assembly does not move to the maximum distance, the bearing assembly will return to its retraction position where the inner rail that not yet reach the desired position will contact the bearings. This makes the movement not smooth as expected. Besides, if the bearing assembly is not moved to the desired position, the connection of exterior equipment to the inner rail is affected.
Furthermore, for the inner rail detachable slide assembly, the inner rail is able to be pulled out from the bearing assembly and separated from the stop base. When the inner rail is to be inserted into the slide assembly and engaged with the bearing assembly from the position where the stop base is located, the bearing assembly has to be in contact with the stop base, such that the inner rail is guided by the stop base to precisely engage with the bearing assembly.
In addition, for the conventional slide assembly, in order to prevent the inner rail from being dropping and retracted when the inner rail is pulled, there is an engaging mechanism located between the inner rail and the stop base. Nevertheless, the engaging mechanism and the movement of the bearing assembly are related to each other. However, under the consideration of reducing manufacturing cost and reducing the number of parts, the above-mentioned mechanism is needed to be improved.
The present invention intends to provide a positioning device that improves the inherent shortcoming which is that the bearing assembly is not moved to the desired position when the inner rail is pulled.